code: def setup_method(self):
      super().setup_method()
      self.metric = BLEU(ngram_weights=(0.5, 0.5), exclude_indices={0})
  
file_path: allennlp/tests/training/metrics/bleu_test.py
imports: from typing import Any, Dict, List, Tuple, Union
  import math
  from collections import Counter
  import torch
  from torch.testing import assert_allclose
  from allennlp.common.testing import AllenNlpTestCase, multi_device, global_distributed_metric, run_distributed_test
  from allennlp.training.metrics import BLEU
  from allennlp.training.util import ngrams, get_valid_tokens_mask
label_desc: Use image node_id 1 for calling the BleuTest obj's underlying member method code with example usage: obj.setup_method() without return types